quote:Originally posted by Djehuti: it is likely that the Khoisan complexion evolved afterward and that their ancestors were much darker when they first settled subtropical Southern Africa.
^Yep.
As a social term, blackness is subjective in nature. Melanin levels are not. Chimu's arguments over black are really political -> he hoped that the original Africans were lighter than equitorial Africans now in order for him to have grounds to challenge that 'African entails black'. He argued that by moving to the South, Africa's oldest (genetically) group retained their ancestral melanin levels.
Genetics has proven the reverse true:
San are an exception-to-the-rule in sub-Saharan Africa in that they have a high occurence of derived alleles, where as other groups generally have a high occurence of the ancestral allele.
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posted
^ Of course and for the reasons cited. mankind did not evolve in the subtropics but in the tropics and the first Eurasians left from East Africa NOT South Africa.
This has been explained to the fool ad-naseum, but logic flies out the window with these centric nutcases-- eurocentric or mixocentric!
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Furthermore, the derived allele and ancestral allele does seem to show a positive correlation with lighter and darker skinned populations, and it seems the frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%). What does this tell you Chimu?
Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians Heather L. Norton,*1 Rick A. Kittles
quote: In contrast, the **ancestral allele** associated with **dark pigmentation** has a shared high frequency in **sub- Saharan African and Island Melanesians**.A notable exception is the relatively lightly pigmented San population of Southern Africa where the **derived allele** predominates (93%), although this may be simply due to small sample size (n514). The distributions of the **derived and ancestral alleles** at TYR A192C, MATP C374G, and SLC24A5 A111G are consistent with the FST results suggesting strong Europeans pecific divergence at these loci. The *derived allele* at TYR, 192*A (previously linked with lighter pigmentation [Shriver et al. 2003]), has a frequency of 38% among European populations but a frequency of only 14% among non-Europeans. The differences between Europeans and non-Europeans for the MATP 374*G and SLC24A5 111*A alleles (both derived alleles associated with lighter pigmentation) were even more striking (MATP European 5 87%; MATP non-European 5 17%; SLC24A5 European 5 100%; SLC24A5 non-European 5 46%). The frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%).
The virtual absence of MATP 374*G–derived allele in the sub-Saharan African populations that we examined in the CEPH-Diversity Panel is consistent with the origin of this mutation outside of Africa after the divergence of modern Asians and Europeans. In contrast, the SLC24A5 111*A–derived allele is found at low frequencies in several sub-Saharan populations including the West African Mandenka and Yoruba, the Southern African San , and SouthWest Bantu. The relatively high frequencies of the derived allele in Central Asian, Middle Eastern, and North Africa seem likely to be due to gene flow with European populations. Similarly, the presence of the derived allele (albeit at low frequencies) in some sub-Saharan African populations may be due to recent gene flow from European and Central Asian populations.
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According to what scale are they described as anything but "dark complexion". What?
Just do a search through old literature.
The Physical Characters of the Sandawe, J. C. Trevor, The Journal of the Royal Anthropological Institute of Great Britain and Ireland, Vol. 77, No. 1 (1947), pp. 61-78.
Immaterial; the burden is on you to produce the scale by which it is said that the Sandawe could not possibly be "dark complexed".
quote:
quote:
What legal document from the Apartheid State said Khoisans, who are not mixed with non-African groups, are anything but in the same camp as "black Africans"? Your link doesn't provide this.
Read below I quote the names of the acts involved.
"Acts" involved is not the same thing as "Official" apartheid state and current South African government census of south African "racial" demography that supports anything you've said; that "Africans" had two camps -- colored and black, which included Khoisans as "colored", and that there was a *separate* colored camp -- which too had Khoisans under the name Griquas. Essentially, you have to back up your claim accordingly, about there being some kind of 5 "racial" categories, as opposed to the often mentioned "4 category".
quote:It is quite obvious though that the Nama, the Khoe, the San, etc were seen as aboriginal, or mixed, but never as Black.
Of course, they were seen as aboriginal, and were only included in the "colored" camp, along with any other person of supposed "mixed" backgrounds, if they 'mixed" with non-African groups, primarily Europeans. Otherwise, the often mentioned "racial" construct was a "4 category" one, wherein thoroughly "aboriginal" Khoisans were included with thoroughly "aboriginal" African groups like the Bantu speakers. You have produced no official document as requested, that suggests otherwise.
quote:Note that the Khoi, San, Nama, and othe rKhoiSanid populations weren't allowed the identity of being an aboriginal tribe, so they were seen as mixed race, Colored, not Black
This is based on the notion that the thoroughly aboriginal Khoisans were nearly wiped out, and the few remaining had since heavily "mixed" with non-Khoisan groups, both foreign and African. But of course, those perceived as thoroughly aboriginal were said to have been placed in the same camp as other aboriginal Africans, namely Bantu speakers.
Now please don't tell me the UNESCO doesn't know what it's talking about.
If you have so much faith in this UNESCO excerpt, then why don't you do the simple task asked of you; to back it up with official South African government census documents about supposed "racial" groups, and their specific ethnic constituents? Can't be that hard, can it?
And even if the government documents didn't place Khoisans in the black group, as you seem to welcome, what bearing does that have on the fact that Khoisans still fall into "dark complexed" continuum, as scales like the Von Luschan suggest?
quote:
quote:This scale doesn't even make sense; what is it suppose to relay; that the higher the score, the lighter? What is the source?
Uh Yeah!?!?
And I'm sure you heard, when it was stated that the same source suggests South African Bantus speakers were even lighter than the Sandawe, right?
quote:
quote:You can't read; the study you are looking at, was from actual geneticists. It's their word. Nobody said anything about Jablonski.
No, you can't read. Kittles was not the primary source If you knew how to read, you would know Kittles paper is making that claim citing Jablonski's paper. Try again.
Indeed I'll try again; if the author's are referencing Jablonski and Chaplin - 2000 on the "derived allele", then please tell us what DNA analysis Jablonski and Chaplin did themselves, and came to the said conclusion...
The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000) - Norton et al.
Norton et al. also say this:
In contrast, the ancestral allele associated with dark pigmentation has a shared high frequency in sub-Sharan African and Island Melanesians. A notable exception is the relatively lightly pigmented San population of Southern Africa where the derived allele predominates (93%), although this may be simply due to small sample size (n=14).
1)Tell me; are they referring to Jablonski's and Chaplin's samples?
2)And even if they were referencing Jablonski and Chaplin 2000, the burden is on you to prove their work wrong; not me. If so, then cite them and tell us what is wrong about their methodologies in sequencing pigmentation alleles, if they ever performed one in the first place.
quote:
quote:If the Khoisans were also classified as "coloreds", then why would they need the term "Griquas" for the other "coloreds" also of Khoisan descent; why?
There is a difference between auto classification, and official classification by law.
Why would people of Khoisan descent be placed under discrete monikers in the "colored"; if they are all viewed "colored" anyway, as you profess, does it not make sense to simply say here, "khoisans are colored". Period. Why all the unnecessary discrete names, like say Khoisan here and Griquas here -- all of Khoisan descent?
quote:
quote:Originally posted by The Explorer: Furthermore...
quote:Until 1991, South African law divided the population into four major racial categories: (1.) The Black Africans, of which the Nguni and Sotho groups account for 90% of the Black population. Black population accounts 75% of the South Africa's entire population. (2.) The Whites who account for about 13% of the population. (3.) The Indians who account for around 3 % and (4.) the Coloreds who are mixed White and Black descent and account for 9% of the population. Although the South African law of racial categories has been abolished, many South Africans still view themselves according to these categories. The black population consists of several groups: Khoi-San, Xhosa, Zulu, Ndebele, Sotho, Shangaan and Venda, just to name a few. The biggest groups are Zulus (21 %), Xhosas (17 %) and the Sotho (15%). Next smaller minorities are the Tswana, Venda, Ndebele, Swasi, and Pedi, among others. The Khoi-Sans are originally hunter-gatherers who have inhabited the land for a long time. Many political leaders, Nelson Mandela among them, come from the Xhosa. Most of the Blacks used to live in the countryside following a traditional way of life, but a class of progressive farmers also formed. Many of these became Christians and had some education from Missionaries. In the towns many Blacks worked as labourers. A small class of professional newspaper editors, lawyers and teachers emerged.
The apartheid regime over-emphasised the differences among the various ethnic group, mainly between whites and non-whites, but also between black groups (i.e. Xhosas and Zulus), and turned them against each other rather than against the government. The policy of racial segregation favoured the political and economic power for the white minority. Until today, South Africa has to deal with the consequences of this disastrous policy. Large part of the fast growing black majority lives in oppressive poverty in the outer districts of the cities lacking sufficient sanitation, electricity and water. Many of the residents are illiterate. The enormous poverty problem in South Africa is the major reason for the high crime rates.
And you don't think the Black majority today aren't imposing their own racial dichotomies today? LMAO.
Wherever did you get the idea about when this structure was set up; according to what official data? It says right up there, in what I cited, "until 1991", and that "Although the South African law of racial categories has been abolished, many South Africans still view themselves according to these categories"; what does that mean to you?
quote: You sure are Naive.
You sure are dense, as seen from your supposed interest in legitimizing the apartheid South African state's racial constructs, as opposed to what you believe -- without producing the source of where you came up with the idea -- that of the current "black" South African government. Going by your rationale, why would apartheid South African state's racial constructs be any better than some supposed one today, under a "black" South African government?
quote: Go read him again.
Read whom; the post I presented? If so, where does it state what you are saying?
quote:
quote:Originally posted by The Explorer:
BTW, what study of uniparental paternal and maternal markers suggest that the Khoisans in Botswana are more "mixed" with "exotic" groups than those in South Africa?
Look at Cavalli-Sforza's work I posted.
What uniparental markers - paternal & maternal - does Sforza's work suggest that South African-based Khoisans are less "mixed" than those in Botswana. The burden is on you to present the evidence, not for me to look it up. If you do that in a court of law, you'd loose a case so fast that your head would spin.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote:Originally posted by MindoverMatter718: Reposted:
Furthermore, the derived allele and ancestral allele does seem to show a positive correlation with lighter and darker skinned populations, and it seems the frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%). What does this tell you Chimu?
Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians Heather L. Norton,*1 Rick A. Kittles
quote: In contrast, the **ancestral allele** associated with **dark pigmentation** has a shared high frequency in **sub- Saharan African and Island Melanesians**.A notable exception is the relatively lightly pigmented San population of Southern Africa where the **derived allele** predominates (93%), although this may be simply due to small sample size (n514). The distributions of the **derived and ancestral alleles** at TYR A192C, MATP C374G, and SLC24A5 A111G are consistent with the FST results suggesting strong Europeans pecific divergence at these loci. The *derived allele* at TYR, 192*A (previously linked with lighter pigmentation [Shriver et al. 2003]), has a frequency of 38% among European populations but a frequency of only 14% among non-Europeans. The differences between Europeans and non-Europeans for the MATP 374*G and SLC24A5 111*A alleles (both derived alleles associated with lighter pigmentation) were even more striking (MATP European 5 87%; MATP non-European 5 17%; SLC24A5 European 5 100%; SLC24A5 non-European 5 46%). The frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%).
The virtual absence of MATP 374*G–derived allele in the sub-Saharan African populations that we examined in the CEPH-Diversity Panel is consistent with the origin of this mutation outside of Africa after the divergence of modern Asians and Europeans. In contrast, the SLC24A5 111*A–derived allele is found at low frequencies in several sub-Saharan populations including the West African Mandenka and Yoruba, the Southern African San , and SouthWest Bantu. The relatively high frequencies of the derived allele in Central Asian, Middle Eastern, and North Africa seem likely to be due to gene flow with European populations. Similarly, the presence of the derived allele (albeit at low frequencies) in some sub-Saharan African populations may be due to recent gene flow from European and Central Asian populations.
Chimu = chumped.
per usual. as expected.
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quote:1)Tell me; are they referring to Jablonski's and Chaplin's samples?
2)And even if they were referencing Jablonski and Chaplin 2000, the burden is on you to prove their work wrong; not me. If so, then cite them and tell us what is wrong about their methodologies in sequencing pigmentation alleles, if they ever performed one in the first place.
Chimu = chumped -> again.
of greater interest than his latest defeat.
difference between Chimu and Akoben.
Chimu - some intelligence, but defeats his own intellect due to bias resulting from debilitating resentments and envies' of Black and 'possibly' White identities.
Akoben- jackass with little to no intelligence. defeats himself everytime he opens his mouth.
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posted
Chimpu just wants every one to be part of his one big international family of "coloreds" or "hybrids". The Sans particularly seem to have a special place in his heart.
^Africans just seem to bring that out in ethno-centric non-Africans, don't they?...selecting an African group here and there, and hold them dear to their hearts. Notwithstanding antagonistic agendas, for Eurocentrists & Medicentrists, it's the East and North Africans; for Mulatto-centrists, now we know that it's the Sans & North Africans. LOL
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote:Originally posted by MindoverMatter718: According to the data..... If the higher the score, lighter the skin. So South African Bantus are lighter than Sandawe, meanwhile Bantus supposedly mixed with Sandawe to make them darker? Sandawe seem like one of the darker observed populations.
[b]Boy are you dense. South African Bantus have also been mixing with San.
Which Khoisan group in South Africa have South African Bantus been mixing with to give them a lighter complexion, and in essence I'd expect these South African Khoisan to be dark skinned..please provide this??
quote:And Sandawe were never as light as San.
Ok, so now you're telling me the Sandawe weren't as light as the San, but wasn't it you who said Sandawe were lighter than a "tanned" Japanese Woman??
But according to this scale, Sandawe appear to be one of the darker populations? You say this is admixture from Bantu? Well then the Sandawe gene pool should reflect this..please show this??
The aboriginal representatives of OOA(Australia, and PNG ) appear extremely darker than the San(from sub-tropical Africa), and there is absolutely NO evidence at all that pigmentation genes for these Oceanic's were selected to become darker. In fact these people carry the ancestral alleles predominately, which ultimately comes from Africa.
India (Southern) 46.7
Mali (Dogon) 34.1
Spain (Basque - Basque and non-Basques) 65.7
Australia (Darwin - Aborigines) 19.3
PNG (Karker - Karker Islanders) 32
Morocco 54.85
Netherlands (Dutch (mainly resident in Utrecht)) 67.37
South African (S. A. Negroes (73% Tswana and Xhosa), Bantu (96% Xhosa)) 42.5
Tanzania (Sandawe) 28.9
Nigeria (Ibo) 28.2
Sudan 35.5
Ireland (Ballinlough) 65.2
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Which Khoisan group in South Africa have South African Bantus been mixing with to give them a lighter complexion, and in essence I'd expect these South African Khoisan to be dark skinned..please provide this??
Chimu would have to pull off a neat trick there, since it was his premise that South African Khoisans are somehow less "mixed" with "non-Khoisan" groups than those in Botswana. I guess he supposes that the Kalahari San "Bushmen" are more "mixed" with non-San groups than those in South Africa. Of course, like I said, notwithstanding this commotion about San skin tones, none of them would fall into anything but "dark complexion" on such scales like the Von Lushcan, and none of them will be "hybrid" groups, as in the sense that Sforza says Europeans are.
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Which Khoisan group in South Africa have South African Bantus been mixing with to give them a lighter complexion, and in essence I'd expect these South African Khoisan to be dark skinned..please provide this??
Chimu would have to pull off a neat trick there, since it was his premise that South African Khoisans are somehow less "mixed" with "non-Khoisan" groups than those in Botswana.
Indeed, which is why I can't wait to hear his response.
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quote:Originally posted by The Explorer: Chimpu just wants every one to be part of his one big international family of "coloreds" or "hybrids". The Sans particularly seem to have a special place in his heart.
^Africans just seem to bring that out in ethno-centric non-Africans, don't they?...selecting an African group here and there, and hold them dear to their hearts. Notwithstanding antagonistic agendas, for Eurocentrists & Medicentrists, it's the East and North Africans; for Mulatto-centrists, now we know that it's the Sans & North Africans. LOL
^ yes, the above psychology and antics were a fundamental strategim for apartheid.
to deny the existence of the indigenous Black majority - it was claid that only the San are Indigenous - and only the Bantu were Black. and, the Blacks have 'their own' separate countries from White majority South Africa.
^ this is what you argue when you're outnumbered, in the wrong, and terrified.
Fear and resentment, are the primary motives behind Chimu's irrationality.
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quote:Originally posted by rasol: ^ yes, the above psychology and antics were a fundamental strategim for apartheid.
to deny the existence of the indigenous Black majority - it was claid that only the San are Indigenous - and only the Bantu were Black. and, the Blacks have 'their own' separate countries from White majority South Africa.
^ this is what you argue when you're outnumbered, in the wrong, and terrified.
Fear and resentment, are the primary motives behind Chimu's irrationality.
Well said.
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I can't help but to wonder what ever happened to the Khoisan obsessed Chimpu? I guess his constant contradictory being caught sent him packing..... Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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^ But knowing the ways of obsessed psycho ideology driven trolls, he'll be back.
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^ Yes and Jaimie (Chimpu) has humiliated himself in other threads as well. And so has assopen. Self-humiliation seems to be an unintended consequence of trolling, especially around here. Posts: 26286 | From: Atlanta, Georgia, USA | Registered: Feb 2005
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quote:Originally posted by The Explorer: Your opinionating that the Bisa Sandawe are "lighter" in no way changes the fact of the study that you are citing above about dark skin alleles in Africans and Melanesians, nor does your *personal* characterization of the Sandawe as "lighter" make them not to be "dark" complexioned folks, that is to say, "black".
And this is an orthochromatic picture for sure, so the older guy could be even lighter. But you still see the difference.
quote:And indeed, they'd have to have ancestral alleles, because after all, that is what's keeping them "dark complexioned". In the meantime,...
The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area. - Norton et al.
Note that while it is said that the allele in question is suggestive of not being a new one, it is recognized as being in the "derived" state.
Sorry but no can do.
quote:From: Heather Norton To: Jaime Andres Pretell Sent: Friday, February 27, 2009 4:29 PM Subject: Re: Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians
Dear Mr. Pretell, Thanks for your interest in my work. Yes, these genes "exist" in other primates. That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc. When we look at the sequence of individual nucleotides (A, C, G, or T) that make up a particular gene, we may see small differences between chimps and humans. So, for example, at one place in the OCA2 gene chimps might all have a "G" base, where humans all carry an "A" in the corresponding position. This is what is known as a fixed difference, and studying fixed differences may help us to understand why humans and chimps differ for certain traits. However, you can imagine that there may be other cases were chimps carry a "G" at a certain position while some humans carry the "G" and others carry an "A". When we see the same nucleotide being carried in both species (in this case, the "G") we call it the ancestral allele. When the nucleotide differs (in this case, the "A") we refer to it as the derived allele. The term allele here is used to refer to a different versions of the same gene. So, while chimps and humans have the same pigmentation genes (so do mice, and pigs, and fish), they may carry slightly different versions of that gene. Sometimes we see slightly different versions of a gene within the same species. These different versions may explain some of the physical differences (like skin pigmentation) that we see among individuals. In other cases, though, these differences don't affect the protein that the gene produces, and so they don't seem to explain physical differences.
The question of the San and Sandawe is an interesting one. We are not sure if the alleles that explain why their pigmentation is so different from neighboring populations reflect new (derived) mutations or if instead maybe they are actually ancestral alleles shared with light-skinned primates. I would say that this is an area of open investigation. As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color. It would be unlikely to be as much variation as we see across the human species today, since today modern humans live in a range of environments where different pigmentation types are more or less adaptive. In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. However, when we look at populations in Africa today (or populations living in other places where ultraviolet radiation is strong) we see a wide range of variation in pigmentation--I suspect that if we could go back in time we would probably see similar levels of diversity to those that we see in Africa today. Thanks again for your interest--if you have any more questions, please let me know. Cheers, ~Heather
Again. Bisa Sandawe lighter than Bantu, and no evidence that it is the derived gene. Norton clearly says that while, like Jabonski, she beleives that the environment will favor darker skin, the genetic allow for the full diversity from the get go, and history has shown us that lighter (as in San and Bisa Sandawe lighter) populations have existed from South Africa all the way to Tanzania. Area for open investigation.
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quote:From: Heather Norton To: Jaime Andres Pretell Sent: Friday, February 27, 2009 4:29 PM Subject: Re: Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians
Dear Mr. Pretell, Thanks for your interest in my work. Yes, these genes "exist" in other primates. That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc. When we look at the sequence of individual nucleotides (A, C, G, or T) that make up a particular gene, we may see small differences between chimps and humans. So, for example, at one place in the OCA2 gene chimps might all have a "G" base, where humans all carry an "A" in the corresponding position. This is what is known as a fixed difference, and studying fixed differences may help us to understand why humans and chimps differ for certain traits. However, you can imagine that there may be other cases were chimps carry a "G" at a certain position while some humans carry the "G" and others carry an "A". When we see the same nucleotide being carried in both species (in this case, the "G") we call it the ancestral allele. When the nucleotide differs (in this case, the "A") we refer to it as the derived allele. The term allele here is used to refer to a different versions of the same gene. So, while chimps and humans have the same pigmentation genes (so do mice, and pigs, and fish), they may carry slightly different versions of that gene. Sometimes we see slightly different versions of a gene within the same species. These different versions may explain some of the physical differences (like skin pigmentation) that we see among individuals. In other cases, though, these differences don't affect the protein that the gene produces, and so they don't seem to explain physical differences.
The question of the San and Sandawe is an interesting one. We are not sure if the alleles that explain why their pigmentation is so different from neighboring populations reflect new (derived) mutations or if instead maybe they are actually ancestral alleles shared with light-skinned primates. I would say that this is an area of open investigation. As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color. It would be unlikely to be as much variation as we see across the human species today, since today modern humans live in a range of environments where different pigmentation types are more or less adaptive. In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. However, when we look at populations in Africa today (or populations living in other places where ultraviolet radiation is strong) we see a wide range of variation in pigmentation--I suspect that if we could go back in time we would probably see similar levels of diversity to those that we see in Africa today. Thanks again for your interest--if you have any more questions, please let me know. Cheers, ~Heather
Again. Bisa Sandawe lighter than Bantu, and no evidence that it is the derived gene. Norton clearly says that while, like Jabonski, she beleives that the environment will favor darker skin, the genetic allow for the full diversity from the get go, and history has shown us that lighter (as in San and Bisa Sandawe lighter) populations have existed from South Africa all the way to Tanzania. Area for open investigation.
Wonder how long you've been waiting for this response.. lol.
In any event, it is clear from Norton's paper she was citing Jablonski on the derived alleles, correct? So why didn't you e-mail Jablonski? As it is pretty clear there are derived alleles that Norton was referencing from Jablonski, correct?
Get back to your email box, and get Jablonski's response on the derived alleles that she notes to be high in the San hunter gatherers of south Africa, then we might give you a chance.
Also, regardless of which way you split it, Norton made clear to you that.....
In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. --NortonPosts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by Chimu: [QUOTE]From: Heather Norton To: Jaime Andres Pretell Sent: Friday, February 27, 2009 4:29 PM
Wonder how long you've been waiting for this response.. lol.
[/qb]
quote:In any event, it is clear from Norton's paper she was citing Jablonski on the derived alleles, correct? So why didn't you e-mail Jablonski? As it is pretty clear there are derived alleles that Norton was referencing from Jablonski, correct?
Wrong. Jablonski never made studies on those genes. Go read the entire study again.
quote:Also, regardless of which way you split it, Norton made clear to you that.....
In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. --Norton
Again, you need to learn the difference of a scientist speculating, "I would say". And stating what she knows for a fact. That the genetic capacity was there to have the same range back then as there is now. And the San and Bisa Sandawe are still there. You also missed the part where she says she is not sure if the light skin of the Bisa Sandawe is the derived form or the ancestral form. Ooops.
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So this derived allele was an imaginary one you're saying, made up fictitiously?
Wouldn't that throw this whole study into question if there is no derived allele and instead it was made up, even though as shown it's specifically mentioned?
Maybe Norton needs to read her study again, because she's clearly contradicting herself.
In any event, you make no sense!
Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians Heather L. Norton,*1 Rick A. Kittles
quote: In contrast, the **ancestral allele** associated with **dark pigmentation** has a shared high frequency in **sub- Saharan African and Island Melanesians**.A notable exception is the relatively lightly pigmented San population of Southern Africa where the **derived allele** predominates (93%), although this may be simply due to small sample size (n514). The distributions of the **derived and ancestral alleles** at TYR A192C, MATP C374G, and SLC24A5 A111G are consistent with the FST results suggesting strong Europeans pecific divergence at these loci. The *derived allele* at TYR, 192*A (previously linked with lighter pigmentation [Shriver et al. 2003]), has a frequency of 38% among European populations but a frequency of only 14% among non-Europeans. The differences between Europeans and non-Europeans for the MATP 374*G and SLC24A5 111*A alleles (both derived alleles associated with lighter pigmentation) were even more striking (MATP European 5 87%; MATP non-European 5 17%; SLC24A5 European 5 100%; SLC24A5 non-European 5 46%). The frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%).
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quote:Originally posted by MindoverMatter718: So this derived allele was an imaginary one you're saying, made up fictitiously?
Wouldn't that throw this whole study into question if there is no derived allele and instead it was made up, even though as shown it's specifically mentioned?
Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians Heather L. Norton,*1 Rick A. Kittles
quote: In contrast, the **ancestral allele** associated with **dark pigmentation** has a shared high frequency in **sub- Saharan African and Island Melanesians**.A notable exception is the relatively lightly pigmented San population of Southern Africa where the **derived allele** predominates (93%), although this may be simply due to small sample size (n514). The distributions of the **derived and ancestral alleles** at TYR A192C, MATP C374G, and SLC24A5 A111G are consistent with the FST results suggesting strong Europeans pecific divergence at these loci. The *derived allele* at TYR, 192*A (previously linked with lighter pigmentation [Shriver et al. 2003]), has a frequency of 38% among European populations but a frequency of only 14% among non-Europeans. The differences between Europeans and non-Europeans for the MATP 374*G and SLC24A5 111*A alleles (both derived alleles associated with lighter pigmentation) were even more striking (MATP European 5 87%; MATP non-European 5 17%; SLC24A5 European 5 100%; SLC24A5 non-European 5 46%). The frequency of the SLC24A5 111*A allele outside of Europe is largely accounted for by high frequencies in geographically proximate populations in northern Africa, the Middle East, and Pakistan (ranging from 62% to 100%).
Hence the reason why I asked Heather Norton herself. hnorton@email.arizona.edu Or ask Rick Kittles. rkittles@africanancestry.com
I'll take her later explanation over your disappointed re-quotation of her original study.
quote:From: Heather Norton To: Jaime Andres Pretell Sent: Friday, February 27, 2009 4:29 PM Subject: Re: Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians
Dear Mr. Pretell, Thanks for your interest in my work. Yes, these genes "exist" in other primates. That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc. When we look at the sequence of individual nucleotides (A, C, G, or T) that make up a particular gene, we may see small differences between chimps and humans. So, for example, at one place in the OCA2 gene chimps might all have a "G" base, where humans all carry an "A" in the corresponding position. This is what is known as a fixed difference, and studying fixed differences may help us to understand why humans and chimps differ for certain traits. However, you can imagine that there may be other cases were chimps carry a "G" at a certain position while some humans carry the "G" and others carry an "A". When we see the same nucleotide being carried in both species (in this case, the "G") we call it the ancestral allele. When the nucleotide differs (in this case, the "A") we refer to it as the derived allele. The term allele here is used to refer to a different versions of the same gene. So, while chimps and humans have the same pigmentation genes (so do mice, and pigs, and fish), they may carry slightly different versions of that gene. Sometimes we see slightly different versions of a gene within the same species. These different versions may explain some of the physical differences (like skin pigmentation) that we see among individuals. In other cases, though, these differences don't affect the protein that the gene produces, and so they don't seem to explain physical differences.
The question of the San and Sandawe is an interesting one. We are not sure if the alleles that explain why their pigmentation is so different from neighboring populations reflect new (derived) mutations or if instead maybe they are actually ancestral alleles shared with light-skinned primates. I would say that this is an area of open investigation. As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color. It would be unlikely to be as much variation as we see across the human species today, since today modern humans live in a range of environments where different pigmentation types are more or less adaptive. In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. However, when we look at populations in Africa today (or populations living in other places where ultraviolet radiation is strong) we see a wide range of variation in pigmentation--I suspect that if we could go back in time we would probably see similar levels of diversity to those that we see in Africa today. Thanks again for your interest--if you have any more questions, please let me know. Cheers, ~Heather
posted
^^^The response you've provided totally contradicts her original study, where derived alleles are specifically mentioned to be present.
Lol, shows where your logic lies, if you have any at all.
I would love to see the e-mail you sent her....please provide it!!
Why would she make a definitive statement about the derived allele like the one below...
The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area. - Norton et al.Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by MindoverMatter718: ^^^The response you've provided totally contradicts her original study, where derived alleles are specifically mentioned to be present.
Lol, shows where your logic lies, if you have any at all.
I would love to see the e-mail you sent her....please provide it!!
I already did. And gave you the email as well. Feel free to email her and confirm. The logic is hers. Not my problem you can't handle it. I suspect that she just assumed derived because they didn't consider the Bisa Sandawe in Tanzania. But that is speculation on my part. You will have to email her and ask her why she recanted on it being derived for sure.
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Maybe Norton needs to read her study again, because she's clearly contradicting herself.
Indeed, that is double speak on Norton's part. In a published journal, it clearly states that the marker is "derived", even though and as expected, it is hard to determine the age of the mutation. Yet, in a personal e-mail correspondence, Norton says that she isn't sure if it is derived, or else "an ancestral" marker, presumably carried over from primate-like ancestors. This doesn't even make sense, considering that the earliest modern humans in the tropics would have needed considerable skin pigmentation to survive. It is just common sense. They didn't have extensive post-cranial body hair like gorillas do. And if they did, I sure would like to see evidence of it, LOL. Paleontological record and quantitative cranio-metric diversity-by-distance model simulations have all implicated tropical Africa as the likely place of origin for modern humanity. Certainly much of KhoiSan territory is below the tropics. Is it then possible, from the tone of Jaime's question, she felt compelled to please him, by telling him what she thinks he probably wanted to hear? I mean this right here, is shaking up her own credibility; the credibility is on the line.
As for the photo spam that Chimu just posted, it makes no difference. These folks would have been sitting at the back of the bus in the U.S., during the Jim Crow era. That right there and then, should educate him on what that means. Moreover, as noted, it is immaterial to the study cited.
quote: In any event, you make no sense!
Ditto. Maybe, Kittles does indeed have to be contacted, to shed light on what's going on here. This doesn't bode well either for the credibility of the published work, or Norton.
-------------------- The Complete Picture of the Past tells Us what Not to Repeat Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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^ Well said. I don't see why we're banking so heavily on personal correspondence. It is clear in literature published that marker associated with pale skin is derived. Her opinions outside of that should be given a lower priority, because bias can't be controlled in this avenue. This is a must in this discussion since it's quite political.
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quote:Originally posted by MindoverMatter718: ^^^The response you've provided totally contradicts her original study, where derived alleles are specifically mentioned to be present.
Lol, shows where your logic lies, if you have any at all.
I would love to see the e-mail you sent her....please provide it!!
I already did.
No, you showed us her response but not your original e-mail, where is it?
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by The Explorer: Indeed, that is double speak on Norton's part. In a published journal, it clearly states that the marker is "derived", even though and as expected, it is hard to determine the age of the mutation.
quote: Yet, in a personal e-mail correspondence, Norton says that she isn't sure if it is derived, or else "an ancestral" marker, presumably carried over from primate-like ancestors. This doesn't even make sense, considering that the earliest modern humans in the tropics would have needed considerable skin pigmentation to survive. It is just common sense. They didn't have extensive post-cranial body hair like gorillas do. And if they did, I sure would like to see evidence of it, LOL. Paleontological record and quantitative cranio-metric diversity-by-distance model simulations have all implicated tropical Africa as the likely place of origin for modern humanity. Certainly much of KhoiSan territory is below the tropics.
The fact remains that they never stated what specific reason why it would be derived in the first place. And the Bisa Sandawe lived in the tropics.
quote:Is it then possible, from the tone of Jaime's question, she felt compelled to please him, by telling him what she thinks he probably wanted to hear? I mean this right here, is shaking up her own credibility; the credibility is on the line.
I don't agree, I think she clarified.
quote:As for the photo spam that Chimu just posted, it makes no difference. These folks would have been sitting at the back of the bus in the U.S., during the Jim Crow era. That right there and then, should educate him on what that means.
It means that they could have been light skinned, I guess.
quote: Moreover, as noted, it is immaterial to the study cited.
Not at all. She stated that the genetics allowed for skin color back then that mirrored the diversity today. That picture elucidates that diversity right on the equator.
quote: Maybe, Kittles does indeed have to be contacted, to shed light on what's going on here. This doesn't bode well either for the credibility of the published work, or Norton.
So contact him. And her. And if you don't think the study or the scientists are credible, don't quote them. But have it as it may, that is her bona fide statement.
quote:Originally posted by MindoverMatter718:
quote:Originally posted by Chimu:
quote:Originally posted by MindoverMatter718: ^^^The response you've provided totally contradicts her original study, where derived alleles are specifically mentioned to be present.
Lol, shows where your logic lies, if you have any at all.
I would love to see the e-mail you sent her....please provide it!!
I already did.
No, you showed us her response but not your original e-mail, where is it?
My original email
quote:Hello Dr. Norton,
Very interesting reading. I was curious, if primates where lighter skinned and then became dark skinned with the evolution of, I believe it was MCR1? Then when humans lightened again in Africa, like the San in South Africa or the Sandawe in Tanzania it could not be any reoccurrence of a prior genetic trait right? So the light skin in primates like the chimp would have nothing to do with derived genes like ASIP or OCA2. Do genes like these even exist in other primates? I was curious if you knew how the Sandawe got comparatively lighter in the equator. Or were they always medium complected within the original gene markers? How much variance can be seen in skin color without ASIP and OCA2 genes? Where all humans the same complexion or was there still a range of skin color possible? Also when you say that they are derived genes, what was the original gene and what is the science to determine which gene was derived from the other?
Sincerely,
Jaime Pretell
You are just grasping at straws because you didn't like her answer.
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quote:Yet, in a personal e-mail correspondence, Norton says that she isn't sure if it is derived,
Hundred bucks that "email" to the blue-eyed white soldier boy Jaime is suspect.
quote:I don't see why we're banking so heavily on personal correspondence. It is clear in literature published that marker associated with pale skin is derived.
quote:Originally posted by Chimu: You are just grasping at straws because you didn't like her answer.
How am I grasping at straws when what she says (?) in an e-mail reply to you completely contradicts her studies results? Lol.
In all actuality, you're the one grasping at straws, because if anyone didn't like her answer it was you, and which is why you felt so compelled to e-mail her, and have her contradict herself therein, right?
As noted it throws this whole study into question, and her credibility to boot, if there are no derived alleles and instead it was made up, even though as shown it's specifically mentioned, understand?
Posts: 6572 | From: N.Y.C....Capital of the World | Registered: Jun 2008
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quote:Originally posted by MindoverMatter718: In all actuality, you're the one grasping at straws, because if anyone didn't like her answer it was you, and which is why you felt so compelled to e-mail her, and have her contradict herself therein,
Indeed, that is double speak on Norton's part. In a published journal, it clearly states that the marker is "derived", even though and as expected, it is hard to determine the age of the mutation.
quote: Yet, in a personal e-mail correspondence, Norton says that she isn't sure if it is derived, or else "an ancestral" marker, presumably carried over from primate-like ancestors. This doesn't even make sense, considering that the earliest modern humans in the tropics would have needed considerable skin pigmentation to survive. It is just common sense. They didn't have extensive post-cranial body hair like gorillas do. And if they did, I sure would like to see evidence of it, LOL. Paleontological record and quantitative cranio-metric diversity-by-distance model simulations have all implicated tropical Africa as the likely place of origin for modern humanity. Certainly much of KhoiSan territory is below the tropics.[
The fact remains that they never stated what specific reason why it would be derived in the first place. And the Bisa Sandawe lived in the tropics.
Take note:
Elsewhere I wrote, with regards to the dichotomy in trends seen between "Original" Inland Melanesians and "CEPH" Island Melanesians:
Further extensions of variations detected amongst Melanesians can be explained by successive demographic events After their African ancestors migrated over 40ky ago. The “original Melanesian sample” appears to have more ancestral pigmentation genes in common with tropical Africans, which is to be expected given that they are direct descendants of the earliest Eurasians, as demonstrated as follows with the OCA2 gene…
In general, the derived allele (associated with lighter pigmentation) is most common in Europeans and East Asians, and the ancestral allele predominates in sub-Saharan Africa and Island Melanesia.
The mutations in the OCA2 gene may well have implications on imparting paleness, as demonstrated in the south African San people…
The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area.
While it seems plausible that the “derived” OCA2 gene came to being before the out-of-Africa migration that give rise to modern Eurasians, it doesn’t appear that this derived allele was necessarily widespread, and may well have been later on selected for in European and East Asians…
Interestingly, derived allele frequencies at this locus are quite different between Native American (15%) and East Asian populations (45%), suggesting that perhaps the derived allele at this locus did not reach very high frequencies in East Asians until after the colonization of the Americas
The pattern observed between the "original" Island Melanesians and the sub-Saharan populations, and that between the "original" Island Melanesians and the "CEPH" Island Melanesians, suggests that OAC2 variations different from those of the former pair, must be derive variants. The shared markers between sub-Saharan African and the "original" Island Melanesians would otherwise have to be explained off by "convergent evolution" at possibly different points in time; what are the odds of that happening at a single locus? However, as suggested above, while the other OAC2 variant-- different from those shared between said sub-Saharans and the "original" Island Melanesian samples--may well be the "derived" variant, it doesn't appear to have emerged after the oft talked about successful OOA migrations of a.m.hs. Thus it could have simply contributed to natural African variation, and then was carried off in modest frequencies with OOA migrants, whereupon it would later be selected for in certain groups [explaining the relatively high frequencies therein], as mentioned above.
So, again, it is hard to determine the ages of the mutations themselves, but from distribution patterns, extrapolations thereof of the molecular chronology of the markers is possible.
quote:
quote: As for the photo spam that Chimu just posted, it makes no difference. These folks would have been sitting at the back of the bus in the U.S., during the Jim Crow era. That right there and then, should educate him on what that means.
It means that they could have been light skinned, I guess.
Sitting at the back of the bus in the Jim Crow era means being "light skinned" to you? I wonder why the "whites" did not think of that then, after all "white skin" is also "light skin"?
Outside your strange fixation with the Sandawe, there is nothing unusual of course, about skin tone variations amongst them in tropical Africa.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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Yawn, your reposting of earlier quotes does not change the fact that you have no direct evidence (as in an actual genetic explanation) that would indicate that one was definitely the derived version and the other the ancestral version.
quote:Originally posted by Chimu:
quote:Originally posted by The Explorer: Your opinionating that the Bisa Sandawe are "lighter" in no way changes the fact of the study that you are citing above about dark skin alleles in Africans and Melanesians, nor does your *personal* characterization of the Sandawe as "lighter" make them not to be "dark" complexioned folks, that is to say, "black".
And this is an orthochromatic picture for sure, so the older guy could be even lighter. But you still see the difference.
quote:And indeed, they'd have to have ancestral alleles, because after all, that is what's keeping them "dark complexioned". In the meantime,...
The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area. - Norton et al.
Note that while it is said that the allele in question is suggestive of not being a new one, it is recognized as being in the "derived" state.
Sorry but no can do.
quote:From: Heather Norton To: Jaime Andres Pretell Sent: Friday, February 27, 2009 4:29 PM Subject: Re: Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians
Dear Mr. Pretell, Thanks for your interest in my work. Yes, these genes "exist" in other primates. That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc. When we look at the sequence of individual nucleotides (A, C, G, or T) that make up a particular gene, we may see small differences between chimps and humans. So, for example, at one place in the OCA2 gene chimps might all have a "G" base, where humans all carry an "A" in the corresponding position. This is what is known as a fixed difference, and studying fixed differences may help us to understand why humans and chimps differ for certain traits. However, you can imagine that there may be other cases were chimps carry a "G" at a certain position while some humans carry the "G" and others carry an "A". When we see the same nucleotide being carried in both species (in this case, the "G") we call it the ancestral allele. When the nucleotide differs (in this case, the "A") we refer to it as the derived allele. The term allele here is used to refer to a different versions of the same gene. So, while chimps and humans have the same pigmentation genes (so do mice, and pigs, and fish), they may carry slightly different versions of that gene. Sometimes we see slightly different versions of a gene within the same species. These different versions may explain some of the physical differences (like skin pigmentation) that we see among individuals. In other cases, though, these differences don't affect the protein that the gene produces, and so they don't seem to explain physical differences.
The question of the San and Sandawe is an interesting one. We are not sure if the alleles that explain why their pigmentation is so different from neighboring populations reflect new (derived) mutations or if instead maybe they are actually ancestral alleles shared with light-skinned primates. I would say that this is an area of open investigation. As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color. It would be unlikely to be as much variation as we see across the human species today, since today modern humans live in a range of environments where different pigmentation types are more or less adaptive. In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. However, when we look at populations in Africa today (or populations living in other places where ultraviolet radiation is strong) we see a wide range of variation in pigmentation--I suspect that if we could go back in time we would probably see similar levels of diversity to those that we see in Africa today. Thanks again for your interest--if you have any more questions, please let me know. Cheers, ~Heather
Again. Bisa Sandawe lighter than Bantu, and no evidence that it is the derived gene. Norton clearly says that while, like Jabonski, she beleives that the environment will favor darker skin, the genetic allow for the full diversity from the get go, and history has shown us that lighter (as in San and Bisa Sandawe lighter) populations have existed from South Africa all the way to Tanzania. Area for open investigation.
quote:Originally posted by Chimu: Yawn, your reposting of earlier quotes does not change the fact that you have no direct evidence (as in an actual genetic explanation) that would indicate that one was definitely the derived version and the other the ancestral version.
quote:Originally posted by Chimu:
quote:Originally posted by The Explorer: Your opinionating that the Bisa Sandawe are "lighter" in no way changes the fact of the study that you are citing above about dark skin alleles in Africans and Melanesians, nor does your *personal* characterization of the Sandawe as "lighter" make them not to be "dark" complexioned folks, that is to say, "black".
And this is an orthochromatic picture for sure, so the older guy could be even lighter. But you still see the difference.
quote:And indeed, they'd have to have ancestral alleles, because after all, that is what's keeping them "dark complexioned". In the meantime,...
The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area. - Norton et al.
Note that while it is said that the allele in question is suggestive of not being a new one, it is recognized as being in the "derived" state.
Sorry but no can do.
quote:From: Heather Norton To: Jaime Andres Pretell Sent: Friday, February 27, 2009 4:29 PM Subject: Re: Genetic Evidence for the Convergent Evolution of Light Skin in Europeans and East Asians
Dear Mr. Pretell, Thanks for your interest in my work. Yes, these genes "exist" in other primates. That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc. When we look at the sequence of individual nucleotides (A, C, G, or T) that make up a particular gene, we may see small differences between chimps and humans. So, for example, at one place in the OCA2 gene chimps might all have a "G" base, where humans all carry an "A" in the corresponding position. This is what is known as a fixed difference, and studying fixed differences may help us to understand why humans and chimps differ for certain traits. However, you can imagine that there may be other cases were chimps carry a "G" at a certain position while some humans carry the "G" and others carry an "A". When we see the same nucleotide being carried in both species (in this case, the "G") we call it the ancestral allele. When the nucleotide differs (in this case, the "A") we refer to it as the derived allele. The term allele here is used to refer to a different versions of the same gene. So, while chimps and humans have the same pigmentation genes (so do mice, and pigs, and fish), they may carry slightly different versions of that gene. Sometimes we see slightly different versions of a gene within the same species. These different versions may explain some of the physical differences (like skin pigmentation) that we see among individuals. In other cases, though, these differences don't affect the protein that the gene produces, and so they don't seem to explain physical differences.
The question of the San and Sandawe is an interesting one. We are not sure if the alleles that explain why their pigmentation is so different from neighboring populations reflect new (derived) mutations or if instead maybe they are actually ancestral alleles shared with light-skinned primates. I would say that this is an area of open investigation. As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color. It would be unlikely to be as much variation as we see across the human species today, since today modern humans live in a range of environments where different pigmentation types are more or less adaptive. In general, I would say that the pigmentation of early humans, who originated in Africa, was dark to provide protection against the damage that ultraviolet radiation can do. However, when we look at populations in Africa today (or populations living in other places where ultraviolet radiation is strong) we see a wide range of variation in pigmentation--I suspect that if we could go back in time we would probably see similar levels of diversity to those that we see in Africa today. Thanks again for your interest--if you have any more questions, please let me know. Cheers, ~Heather
Again. Bisa Sandawe lighter than Bantu, and no evidence that it is the derived gene. Norton clearly says that while, like Jabonski, she beleives that the environment will favor darker skin, the genetic allow for the full diversity from the get go, and history has shown us that lighter (as in San and Bisa Sandawe lighter) populations have existed from South Africa all the way to Tanzania. Area for open investigation.
Do you have any paper regarding melanin level suggesting that? Just because someone (whoever they are) may observe that doesn't mean it's true.
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According to Jablonski and Chaplin 2000's study, Sandewe has similar reflectance levels as Namibians or those from Zaire. The San populations found in Botswana and South Africa are much lighter. That excerpted posted by Mind suggesting that San has a high level of derived alleles also include San populations with higher reflectance levels.
posted
Salassinboy is only trying to revive his bait argument from this thread under the guise of a suspect email.
Here he is trying to revive the Coonian Capoid race theory, "KhoiSan maybe distantly related to Bantu, but are still sufficiently genetically separate to be as distant as Asians are to Europeans."
Yawn, your reposting of earlier quotes does not change the fact that you have no direct evidence (as in an actual genetic explanation) that would indicate that one was definitely the derived version and the other the ancestral version.
I just gave you an actual *genetic explanation*, the one actually published and conducted by a group of geneticists, and not a personal correspondence with one participant, as to why the most parsimonious explanation of OAC2 variant--implicated in Sans and later in Europeans and East Asians--is one wherein it could only have been a derived allele, as opposed to the upstream one. This explanation is *supported* by the study, as cited! You simply did not understand, nor capable of addressing the point brought forth head on, and so, you just chose to ignore it. Norton's personal correspondence to you, does NOT address the points I raised, and so, you cannot use that as some sort of rebuttal. The onus is on either you or Norton to explain why that pattern of findings is so, other than the one provided by both myself, AND the published journal itself. Your response, or rather non-response, is immaterial to what I just raised about the patterns of DNA findings in the samples studied.
Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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Here's an even easier challenge than addressing my earlier post above, which is apparently too difficult for Chimu: Give us this "ancestral OCA2" marker shared between primates and humans!
-------------------- The Complete Picture of the Past tells Us what Not to Repeat Posts: 7516 | From: Somewhere on Earth | Registered: Jan 2008
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quote:Originally posted by The Explorer: Take note:
Elsewhere I wrote, with regards to the dichotomy in trends seen between "Original" Inland Melanesians and "CEPH" Island Melanesians:
Further extensions of variations detected amongst Melanesians can be explained by successive demographic events After their African ancestors migrated over 40ky ago. The “original Melanesian sample” appears to have more ancestral pigmentation genes in common with tropical Africans, which is to be expected given that they are direct descendants of the earliest Eurasians, as demonstrated as follows with the OCA2 gene…
quote:As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color.
quote:That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc.
quote:In general, the derived allele (associated with lighter pigmentation) is most common in Europeans and East Asians, and the ancestral allele predominates in sub-Saharan Africa and Island Melanesia.
Nice strawman. The derived gene in Europeans and Asians, is not the gene responsible for lightness in the Bisa Sandawe.
quote:Three loci, TYR A192C, MATP C374G, SLC24A5 A111G, show very strong signals of European-specific divergence. At all 3 loci, Europeans have the highest frequency of the derived alleles relative to the other 5 populations.
The San so called derived gene is
quote:At OCA2 355, the derived allele (linked with lighter pigmentation) occurs at its highest frequencies across Europe and Asia but is also relatively common among Native American populations (18–34%) and is present at much lower frequencies (0–10%) among Bantu-speaking African groups. In contrast, the ancestral allele associated with dark pigmentation has a shared high frequency in sub-Saharan African and Island Melanesians. A notable exception is the relatively lightly pigmented San population of Southern Africa where the derived allele predominates (93%), although this may be simply due to small sample size (n = 14).
Note that there is an ASSUMPTION that it is derived because of the lack of frequency in Melanesians and Africans, but there is NO EXPLANATION as to why the San's allele would be derived. In other words, a hypothesis. And when pressed, Dr. Norton stated succinctly, that they didn't know for sure.
quote:The mutations in the OCA2 gene may well have implications on imparting paleness, as demonstrated in the south African San people…
The lightly pigmented hunter-gatherer San populations of Southern Africa is exceptional in having a high frequency of the derived allele relative to geographically proximate and more darkly pigmented African populations (Jablonski and Chaplin 2000), further supporting the importance of OCA2 in regulating normal variation in pigmentation. The widespread distribution of the derived allele in the CEPH-Diversity Panel suggests that it is not necessarily a new mutation, nor has it been restricted to a specific geographic area.
quote:The question of the San and Sandawe is an interesting one. We are not sure if the alleles that explain why their pigmentation is so different from neighboring populations reflect new (derived) mutations or if instead maybe they are actually ancestral alleles shared with light-skinned primates. I would say that this is an area of open investigation.
quote:While it seems plausible that the “derived” OCA2 gene came to being before the out-of-Africa migration that give rise to modern Eurasians, it doesn’t appear that this derived allele was necessarily widespread, and may well have been later on selected for in European and East Asians…
Interestingly, derived allele frequencies at this locus are quite different between Native American (15%) and East Asian populations (45%), suggesting that perhaps the derived allele at this locus did not reach very high frequencies in East Asians until after the colonization of the Americas
The pattern observed between the "original" Island Melanesians and the sub-Saharan populations, and that between the "original" Island Melanesians and the "CEPH" Island Melanesians, suggests that OAC2 variations different from those of the former pair, must be derive variants. The shared markers between sub-Saharan African and the "original" Island Melanesians would otherwise have to be explained off by "convergent evolution" at possibly different points in time; what are the odds of that happening at a single locus? However, as suggested above, while the other OAC2 variant-- different from those shared between said sub-Saharans and the "original" Island Melanesian samples--may well be the "derived" variant, it doesn't appear to have emerged after the oft talked about successful OOA migrations of a.m.hs. Thus it could have simply contributed to natural African variation, and then was carried off in modest frequencies with OOA migrants, whereupon it would later be selected for in certain groups [explaining the relatively high frequencies therein], as mentioned above.
So, again, it is hard to determine the ages of the mutations themselves, but from distribution patterns, extrapolations thereof of the molecular chronology of the markers is possible.
Again, dealing with derived genes in Asians, not the supposed derived gene in Sandawe.
quote:Originally posted by Bob_01: Do you have any paper regarding melanin level suggesting that? Just because someone (whoever they are) may observe that doesn't mean it's true.
1947-Trevor-The Physical Characters of the Sandawe
quote:Originally posted by Bob_01: According to Jablonski and Chaplin 2000's study, Sandewe has similar reflectance levels as Namibians or those from Zaire. The San populations found in Botswana and South Africa are much lighter. That excerpted posted by Mind suggesting that San has a high level of derived alleles also include San populations with higher reflectance levels.
That would be the Tehla Sandawe. The Sandawe have been mixing extensively with Bantu populations.
quote:From: "Imogene Lim" To: "Jaime Pretell" Sent: Tuesday, July 29, 2008 7:17 PM Subject: RE: Rock-shelter Use Today: An Indicator of Usandawe Prehistory
If you look at recent photographs, there has been increasing intermarriage between groups. Certainly when I conducted my field work some 20 years ago, there were those who shared strong resemblance to their southern counterparts, the Ju/'hoansi and other Bushmen/San, the only other true Khoisan language speakers. After being in the field over a year, I was "darker" in skin tone than many of the Sandawe in the community where I lived.
Eric Ten Raa who studied among the Sandawe in the early 1960s has photographs in one particular article showing the distinction between the Tehla and Bisa Sandawe. The latter are the ones who exhibit the classic Sandawe phenotype.
Regards, Imogene
quote:Originally posted by The Explorer: I just gave you an actual *genetic explanation*, the one actually published and conducted by a group of geneticists, and not a personal correspondence with one participant, as to why the most parsimonious explanation of OAC2 variant--implicated in Sans and later in Europeans and East Asians--is one wherein it could only have been a derived allele, as opposed to the upstream one. This explanation is *supported* by the study, as cited!
Nice try. Not supported by the study. A statement of fact was made, but no actual evidence was provided. And Dr. Norton clarified that they really did not know.
quote:Originally posted by The Explorer: Here's an even easier challenge than addressing my earlier post above, which is apparently too difficult for Chimu: Give us this "ancestral OCA2" marker shared between primates and humans!
Humans are primates. And irrelevant question. you have yet to show anything other than conclusive statements that the OCA2 in San is derivative.
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quote:Originally posted by The Explorer: Take note:
Elsewhere I wrote, with regards to the dichotomy in trends seen between "Original" Inland Melanesians and "CEPH" Island Melanesians:
Further extensions of variations detected amongst Melanesians can be explained by successive demographic events After their African ancestors migrated over 40ky ago. The “original Melanesian sample” appears to have more ancestral pigmentation genes in common with tropical Africans, which is to be expected given that they are direct descendants of the earliest Eurasians, as demonstrated as follows with the OCA2 gene…
quote:As for ASIP and OCA2...I think that even if you ignored the contribution of these two genes to pigmentation variation we would still see good range of diversity. For example, genes like SLC24A5 and MATP also have a major impact on phenotype. I would also assume that in the past there was variation in human skin color.
quote:That is to say, primates have stretches of DNA sequence that produce the same protein in humans and in chimps, and these are usually found in the same corresponding region on their chromosomes. So, it would be correct to say that both humans and chimps, for example, have the gene for ASIP, OCA2, MC1R, etc.
quote:In general, the derived allele (associated with lighter pigmentation) is most common in Europeans and East Asians, and the ancestral allele predominates in sub-Saharan Africa and Island Melanesia.
Nice strawman. The derived gene in Europeans and Asians, is not the gene responsible for lightness in the Bisa Sandawe.
Clown, the strawman is your response, since it has nothing to do with my post. Take note, Chimu has not even addressed the point made, and instead just blindly copies & pastes random notes from his personal correspondence.
quote: Note that there is an ASSUMPTION that it is derived because of the lack of frequency in Melanesians and Africans, but there is NO EXPLANATION as to why the San's allele would be derived. In other words, a hypothesis. And when pressed, Dr. Norton stated succinctly, that they didn't know for sure.
It is called the most parsimonious explanation of the pattern seen. And you are dead wrong. There is a definitive pattern here: The "original" Island Melanesian samples consistently share ancestral alleles with sub-Saharan African samples for many of the pigmentation alleles studied; whereas this was not always the case with the "CEPH" panel Island Melanesians. The "original" Island Melanesians look to be a group that received relatively less subsequent waves of migration from exotic groups than the CEPH panel counterpart. This explains why they also share more ancestral markers than the CEPH panel counterpart, with sub-Saharan Africans. Virtually every group that has ever been implicated in ancestral alleles, had also been done so, in tandem with sub-Saharan Africans. This pattern is suggestive of the prospect that the ancestral allele(s) is (are) the one that predominates in sub-Saharan Africans, and the derived ones came later. It is against this backdrop, it was observed that the OCA2 example frequent [according to the study at hand] in southern African San, Europeans and East Asians, must be the later arrival of the examples seen in African populations. Fact is, the observation that the said OCA2 allele--as seen in the San--is derived is not an aberration; it was deliberatly thought of as one in the study, hence, contradicting your position that the authors were not sure about their findings. It had not been stated once, but several times throughout the study.
quote: Again, dealing with derived genes in Asians, not the supposed derived gene in Sandawe.
Red herring. Staying on-topic is not amongst your talents. The issue at hand is OCA2 derived allele in the San. Nobody spoke of the Sandawe, the folks you seem particularly obsessed with. But since you keep bringing them up for no apparent reason, the burden is on you to demonstrate to us what OCA allele the Sandawe supposedly carry.
quote:
quote:Originally posted by The Explorer: I just gave you an actual *genetic explanation*, the one actually published and conducted by a group of geneticists, and not a personal correspondence with one participant, as to why the most parsimonious explanation of OAC2 variant--implicated in Sans and later in Europeans and East Asians--is one wherein it could only have been a derived allele, as opposed to the upstream one. This explanation is *supported* by the study, as cited!
Nice try. Not supported by the study.
As in which part? Point it out, and why it is so.
quote: A statement of fact was made, but no actual evidence was provided.
It was presented, backed by citations of findings from the published study, not personal chit chat. Just admit that you don't comprehend what was said, and you are not equipped to provide a substantiated rebuttal. I won't hold it against you.
quote: And Dr. Norton clarified that they really did not know.
Norton's personal correspondence does NOT account for the observations seen in the study, as I had already told you in the last post. This therefore, makes your stuck-on-record citation of a personal correspondence outmoded. It has outlived it usefulness, because you are now confronted with explaining away a definitive pattern reported by the geneticists in the study. This definitive pattern, and the geneticists observations made thereof, says that Norton is either suggesting she and the other geneticists are liars, who publish things they did not observe, OR, that she isn't being frank with you. You take your pick; or else, let's see your counter-substantiation, instead of using that outmoded personal correspondence, which is incapable of addressing what I just pointed out.
quote:
quote:Originally posted by The Explorer: Here's an even easier challenge than addressing my earlier post above, which is apparently too difficult for Chimu: Give us this "ancestral OCA2" marker shared between primates and humans!
Humans are primates. And irrelevant question.
Which is why Norton also mentioned them? Tell me you are just fooling around, and you cannot possibly be that obtuse, not to know what is being said.
quote: you have yet to show anything other than conclusive statements that the OCA2 in San is derivative.
Already shown, and as already demonstrated, you don't understand what I just explained, it is too complicated for your faculty, let alone have a substantive counter-reply to show, other than spaming an e-mail correspondence that has outlived its purpose...for you. Your correspondence raised the possibility that the "derived" allele may actually turn out to be an ancestral one shared with primates [which you claim is irrelevant]. It should be easy then; show us this said "shared" allele between humans and "light skinned" primates.
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quote:Fact is, the observation that the said OCA2 allele--as seen in the San--is derived is not an aberration; it was deliberatly thought of as one in the study, hence, contradicting your position that the authors were not sure about their findings. It had not been stated once, but several times throughout the study.
Exactly, plain and simple, it was mentioned more than once, it wasn't a slip up, and this is the point that Chimpu fails to comprehend, he's grasping at straws with his personal correspondance as if it trumps the studies numerous confirmations of this derived allele being present, it simply can't, her correspondence wasn't peer reviewed as the study was, of course this is why he took a year to come back and reply.
quote: It should be easy then; show us this said "shared" allele between humans and "light skinned" primates.
In essence wouldn't this imply that there were different primate ancestors to anatomically modern humans, as it is pretty much known around 1.2 million years ago our primate ancestors lost their fur and needed this deeply melanized skin.
Btw, I sent H. Norton and R. Kittles an e-mail about this derived allele, and am currently awaiting a reply....
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In essence wouldn't this imply that there were different primate ancestors to anatomically modern humans, as it is pretty much known around 1.2 million years ago our primate ancestors lost their fur and needed this deeply melanized skin.
The idea here is presumably, that modern primates [not talking about "humans", as Chimu intentionally confuses himself with] may still carry an OCA2 allele that is associated with lighter pigment [the reason being, presumably, that our common ancestors had been extensively covered with fur or body hair], since their post-cranial body are heavily covered with fur, usually hiding lightly pigmented skin...which they could potentially share with certain recent humans. The implication then, is that this marker may not necessarily have undergone mutation and selection thereof--in contrast to the example that would have produced dark skin in the earliest humans, who did away with extensive post-cranial body hair--in all of the human populations. In other words: the "older" lighter-pigment-invoking OCA2 allele was retained for some humans, while it must undergone a nonsynonymous mutation characterizing darker pigmentation across the rest of humanity, at an early point of human biohistory. The pattern of distribution of these alleles, as I have demonstrated however, suggest that if this marker was around at an early point, i.e. before the often talked about OOA dispersions, then it clearly was not widespread. It must have been randomly around at modest frequencies. There is a problem with this mentality though, because while humanity's ape-like ancestors, bearing thick fur, could have had some OCA2 allele that was lax in pigment phenotype, it doesn't necessarily hold true that the earliest anatomically modern humans had this same allele. This allele could have undergone mutation in our earliest "upright"-walking ancestors, like the Homo Erectus, who had by then, already done away with extensive postcranial body "fur" or hair that earlier hominids likely had. This new allele could have just been carried over to anatomically modern human, who too, did away with body hair...or yet, gave a step mutation(s) that caused more pigmentation in the earliest modern humans of the tropics [the home latitudes of modern humans].
On the other hand, is it possible that OCA2 reverted back to an earlier form in some populations, by way of mutation? Well, what are the odds of that happening? Whatever the case may be, it would have to be dependent on and revolving around whether the "light-pigment" OCA2 alleles in humans is the exact replica found in other primates, presumably those hiding lightly pigment skin under their fur.
And even if one were to assume that the "light-pigment" OCA2 variant is the earlier molecular state, its function in the earliest modern humans in the tropics, would have been at best, in "normal variation" across them...meaning, that they would still have been dark skin folks, with varying degrees of considerable skin melanin.
quote: Btw, I sent H. Norton and R. Kittles an e-mail about this derived allele, and am currently awaiting a reply....
Good. There is definitely some explaining to do here. Norton's claim is at odds with the patterns seen in their findings and the extrapolations made thereof. This either says that she is tacitly saying that she and her colleagues simply published observations that DID NOT HAPPEN...Or...she wasn't being entirely open or frank with Chimu/Jaime. These are the two outcomes we will soon verify, should they see it fit to reply your inquiry. Of course, one cannot speak of absolute certainty in these circumstances, but there is such as thing as the most parsimonious explanation based on the weight of evidence, and this, I think, is what the published article was telling us.
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posted
LOL. Nice try. I don't have to show a common ancestral allele of OCA2 in other primates and the San. The San are darker than a primate like the Chimpanzee. But they are not as dark as the Bantu. All humans would have derived OCA2 from ancient primates. But some derivations could have been earlier and not as divergent, and stuck around, like the that of the Sandawe. No evidence against it.
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LOL. Nice try. I don't have to show a common ancestral allele of OCA2 in other primates and the San.
Yes, you DO. Your personal correspondance attempts to muddle up the non-accidental consideration of the San OCA2 allele example as the derived variant, by arguing that the said allele could be shared with primates, and hence, could be indicative of an ancestral allele. It is therefore either your responsibility or Norton's to point out this common ancestral allele.
quote: The San are darker than a primate like the Chimpanzee. But they are not as dark as the Bantu. All humans would have derived OCA2 from ancient primates.
Red herring; what else is new from you? The matter at hand is THE ancestral *modern human allele*, not "ancient primates".
quote: But some derivations could have been earlier and not as divergent, and stuck around, like the that of the Sandawe. No evidence against it.
Mindless. This has no relevancy to the discussion as you neither know what allele the Sandawe bear, nor is the Sandawe an issue even though you love to talk about them. You just like to shoot off-tangent blanks that don't make sense, and stall your delivery of the actual evidence requested of you. This is because, all you've got is that correspondence, outside of which you understand very little about the subject matter at hand. This is why you also incoherently answered my post, which is not addressed by your correspondence, with outmoded regurgitations of pieces from that correspondence, that don't follow what you are replying to.
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